You are absolutely right to check that directory... Let's try a different and often more effective method. We will use two standard Linux tools, `partprobe` and `udevadm`... Please run these commands as **root**:

1.  **First, remove the `/dev/sdb` entry again:**
    ```bash
    echo 1 > /sys/block/sdb/device/delete
    ```

2.  **Force the kernel to re-read partition tables on all devices.**
    ```bash
    partprobe
    ```

3.  **Trigger `udev` to re-process all devices.**
    ```bash
    udevadm trigger
    ```

4.  **Check the result:**
    ```bash
    cat /proc/partitions
    ```